Amino Acid Chelates of Titanium and Use Thereof in Aqueous Titanation of Polymerization Catalysts

ABSTRACT

A method comprising contacting a silica support with a titanium-containing solution to form a titanated silica support, wherein the titanium-containing solution comprises a titanium compound, a solvent, and an amino acid.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 16/861,705, filed on Apr. 29, 2020 and published as U.S. PatentApplication Publication No. 2020/0392265 A1, which is a continuation ofU.S. patent application Ser. No. 16/439,067, filed on Jun. 12, 2019 andpublished as U.S. Patent Application Publication No. 2020/0392261 A1,both entitled “Amino Acid Chelates of Titanium and Use Thereof inAqueous Titanation of Polymerization Catalysts,” both of which areincorporated by reference herein in their entirety.

TECHNICAL FIELD

The present disclosure relates to catalyst compositions. Morespecifically, the present disclosure relates to methods of preparingolefin polymerization catalyst compositions and polymers prepared fromsame.

BACKGROUND

An economically important class of olefin polymerization catalystsincludes chromium-silica-titanium (Cr/Si—Ti) catalysts prepared fromsilica-based catalyst supports. Rigorous drying of the water-sensitivecatalyst components used to produce Cr/Si—Ti catalysts increases thetime and cost of production. Development of an aqueous solution suitablefor depositing titanium onto a silica-based catalyst support wouldreduce the costs of production of olefin polymerization catalysts. Thus,there is an ongoing need to develop new methods of producing olefinpolymerization catalysts.

SUMMARY

Disclosed herein is a method comprising contacting a silica support witha titanium-containing solution to form a titanated silica support,wherein the titanium-containing solution comprises a titanium compound,a solvent, and an amino acid.

While the subject matter disclosed herein is susceptible to variousmodifications and alternative forms, only a few specific aspects havebeen shown by way of example and are described below in detail. Thedetailed descriptions of these specific aspects are not intended tolimit the breadth or scope of the subject matter disclosed or theappended claims in any manner. Rather, the detailed written descriptionsare provided to illustrate the present disclosure to a person skilled inthe art and to enable such person to make and use the concepts disclosedherein.

DETAILED DESCRIPTION

The present disclosure encompasses olefin polymerization catalysts andpre-catalyst compositions thereof, methods of preparing olefinpolymerization catalysts and pre-catalyst compositions thereof, andmethods of utilizing olefin polymerization catalysts. In an aspect, amethod of the present disclosure comprises contacting a silica supportor a chromium-silica support (i.e., support) with titanium to produce aCr/Si—Ti catalyst. The methodologies disclosed herein contemplate theuse of a titanium-containing solution (e.g., an aqueous titaniumsolution (ATS)) to facilitate the association of titanium with thesupport (e.g., in the presence of water). In an aspect, a methodologyfor preparation of the olefin polymerization catalyst comprisescontacting a chromium-silica support with the titanium-containingsolution (e.g., ATS) under conditions suitable to form a pre-catalystcomposition and further processing the pre-catalyst composition toproduce a Cr/Si—Ti catalyst. In an alternative aspect, a methodology forpreparation of the olefin polymerization catalyst comprises contacting(e.g., simultaneously or sequentially) a silica support with thetitanium-containing solution and a chromium-containing compound (e.g.,an ATS further comprising a chromium-containing compound) underconditions suitable to form a pre-catalyst composition and furtherprocessing the pre-catalyst composition to produce a Cr/Si—Ti catalyst.While these aspects may be disclosed under a particular heading, theheading does not limit the disclosure found therein. Additionally, thevarious aspects disclosed herein can be combined in any manner.

Aspects of the present disclosure are directed to catalyst compositionsand pre-catalyst compositions. In an aspect, a catalyst compositioncomprises an olefin polymerization catalyst (e.g., a Cr/Si—Ti catalyst).In a further aspect, the olefin polymerization catalyst comprises atreated pre-catalyst composition. In yet a further aspect, the treatedpre-catalyst composition comprises a pre-catalyst composition that hasbeen subjected to an activation treatment (e.g., calcination, optionallysubsequent to drying) as disclosed herein.

Disclosed herein are methods of making pre-catalyst compositions andpre-catalyst compositions made thereby. In an aspect, a method of makinga pre-catalyst composition comprises contacting a silica support with atitanium-containing solution to form a titanated silica support, whereinthe titanium-containing solution is formed by contacting (in any order)a solvent (e.g., water); an amino acid; optionally a peroxide;optionally a carboxylate; and a titanium-containing compound (alsoreferred to herein as a “titanium compound”). The method may furthercomprise contacting a chromium-containing compound with the silicasupport or the titanated silica support, and the support may be driedbefore and/or after contact with the chromium-containing compound. In anaspect, the titanium-containing solution further comprises thechromium-containing compound.

In an aspect, a method of making a pre-catalyst composition comprisescontacting a chromium-silica support with aqueous titanium solution toform a titanated/chrominated silica support, wherein thetitanium-containing solution is formed by contacting (in any order)water; an amino acid; optionally a peroxide; optionally a carboxylate;and a titanium-containing compound.

In an aspect, a method of making a pre-catalyst composition comprisescontacting a chromium-silica support with aqueous titanium solution toform a titanated/chrominated silica support, wherein thetitanium-containing solution is formed by contacting (in any order)water; an amino acid, a peroxide; and a titanium-containing compound.

In an aspect, a method of making a pre-catalyst composition comprisescontacting a chromium-silica support with aqueous titanium solution toform a titanated/chrominated silica support, wherein thetitanium-containing solution is formed by contacting (in any order)water; an amino acid, a carboxylate; and a titanium-containing compound.

In an aspect, a method of making a pre-catalyst composition comprisesdissolving a titanium-containing compound (e.g., a titanium alkoxide) inan aqueous solution (e.g., water) comprising an amino acid andoptionally a peroxide or a carboxylate to form an aqueous titaniumsolution (ATS); contacting a silica support with the aqueous titaniumsolution to form a titanated support; and drying the titanated supportto form a dried titanated support; wherein chromium is added bycontacting the silica support, the titanated support, the driedtitanated support, or a combination thereof with a chromium-containingcompound (also referred to herein as a “chromium compound”) to form thepre-catalyst composition.

A method of forming a pre-catalyst composition or catalyst of thisdisclosure comprises forming a titanium-containing solution (e.g., anaqueous titanium solution (ATS)) by contacting a solvent; an amino acid;optionally a peroxide; optionally a carboxylate; and a titaniumcompound. The titanium-containing solution (e.g., ATS) can be formed bycombining the solvent; the amino acid; optionally a peroxide; optionallya carboxylate; and the titanium compound in any suitable order. In aparticular aspect, an ATS of the present disclosure is formed bycontacting water, an amino acid, optionally a peroxide, optionally acarboxylate, and a titanium-containing compound (e.g., titaniumalkoxide). In aspects, the titanium-containing solution comprises,consists essentially of, or consists of a combination of the solvent;the amino acid; optionally a peroxide; optionally a carboxylate; and thetitanium compound. In aspects, the aqueous titanium solution (ATS)comprises, consists essentially of, or consists of a combination ofwater; the amino acid; optionally a peroxide; optionally a carboxylate;and the titanium compound. In aspects, the aqueous titanium solution(ATS) comprises, consists essentially of, or consists of a combinationof water; the amino acid; a peroxide; and the titanium compound. Inaspects, the aqueous titanium solution (ATS) comprises, consistsessentially of, or consists of a combination of water; the amino acid; acarboxylate; and the titanium compound.

In an aspect, the titanium-containing solution of the present disclosurecomprises a solvent. The solvent may be an aqueous solvent, an alcohol,a ketone, or a combination thereof. In an aspect, the solvent compriseswater and the resultant solution is an aqueous titanium solution (ATS).A non-limiting example of an aqueous solvent suitable for use in thepresent disclosure comprises deionized water, distilled water, filteredwater, or a combination thereof. Non-limiting examples of alcoholssuitable for use as the solvent include methanol, ethanol, n-propanol,isopropanol, n-butanol, isobutanol, pentanol, hexanol, cyclohexanol,heptanol, octanol, benzyl alcohol, phenol, or a combination thereof.Examples of ketones include acetone, 2-pentanone, 3-hexanone, and thelike.

In a particular aspect, the titanium-containing solution (e.g., ATS) asdisclosed herein comprises an amino acid. In an aspect, the amino acidcomprises an alpha (α) amino acid, a beta (β) amino acid, or acombination thereof, wherein an α amino acid is an amino acid having anamino group and a carboxyl group attached to the alpha carbon, andwherein a β amino acid is an amino acid in which the amino group isattached to the secondary carbon. In aspects, the amino acid comprisesan “essential” amino acid meaning an amino acid that cannot be made bythe human body but must be supplied by food. In an aspect, the essentialamino acid comprises histidine, isoleucine, leucine, lysine, methionine,phenylalanine, threonine, tryptophan, valine, or a combination thereof.In aspects, the amino acid comprises a γ hydroxyl (OH⁻) group. In anaspect, the amino acid comprises glycine, dimethylglycine, threonine,serine, aspartic acid, arginine, or a combination thereof. In an aspect,the amino acid comprises dimethylglycine, threonine, or a combinationthereof.

In an aspect, a titanium-containing solution (e.g., ATS) of the presentdisclosure comprises an amino acid solution having a weight ratio ofsolvent to amino acid in a range of from about 1 to about 1000;alternatively, from about 5 to about 500; or alternatively, from about10 to about 100. In a further aspect, the ATS comprises a molar ratio ofamino acid to titanium in a range of from about 0.1 to about 10;alternatively, from about 0.5 to about 5; or alternatively, from about 1to about 3. In some aspects, the equivalent molar ratio of amino acid tothe titanium-containing compound may be in a range of from about 2 toabout 3. Also, it is expected that the molar ratio of the components(e.g., amino acid, optional peroxide, optional carboxylate, andtitanium) present in the titanium-containing solution (e.g., ATS) willlikewise be present upon impregnation of the silica support and dryingthereof to form a pre-catalyst.

In some embodiments, the titanium-containing solution (e.g., aqueoustitanium solution (ATS)) of this disclosure comprises a peroxide. Inaspects, the peroxide comprises hydrogen peroxide (H₂O₂), dicumylperoxide, benzoyl peroxide, di-t-butyl peroxide, t-butyl hydroperoxide,a per-carboxylic acid, a peroxy acid, a perester, and the like, or acombination thereof. Although a variety of peroxides, including organicperoxides, can be utilized, in aspects, the peroxide comprises hydrogenperoxide (H₂O₂). The use of hydrogen peroxide can minimize HRVOCemissions during calcining of the pre-catalyst composition to producethe catalyst.

Nonlimiting examples of organic peroxides suitable for use in thisdisclosure include dialkyl peroxides, dicumyl peroxide, di-t-butylperoxide, 2,5-dimethyl-2,5-di-(t-butylperoxy) hexane (DHBP), diacylperoxides, dilauroyl peroxide, dibenzoyl peroxide, peroxyesters, t-butylperoxy-2-ethylhexanoate, OO-(t-butyl)-O-(2-ethylhexyl) peroxycarbonate,t-butyl peroxy-3,5,5-trimethylhexylhexanoate, t-butyl peroxy benzoate,diperoxyketals, diacyl peroxides, t-amyl peroxides,n-butyl-4,4-di-(t-butyl peroxy) valerate, and the like, or combinationsthereof.

In an aspect of the titanium-containing solution, the amino acid isthreonine and the peroxide is hydrogen peroxide.

When used as described herein, the peroxide can be present in thetitanium-containing solution (e.g., ATS) in an amount of about 1 toabout 100 mol of peroxide per mol of Ti present, alternatively, in anamount of about 1 to about 50 mol of peroxide per mol of Ti present;alternatively in an amount of about 1 to about 10 mol of peroxide permol of Ti present; or alternatively in an amount of about 3 to about 10mol of peroxide per mol of Ti present. In aspects, thetitanium-containing solution (e.g., ATS) can contain from about 1% toabout 25, from about 5 to about 20, or from about 8 to about 15 weightpercent (wt %) hydrogen peroxide, based on a total weight of the aqueoustitanium solution.

In some embodiments, the titanium-containing solution (e.g., aqueoustitanium solution (ATS)) of this disclosure comprises a carboxylate. Inaspects, the carboxylate is provided via addition of a carboxylic acidto the titanium-containing solution. The carboxylic acid can comprise amonocarboxylic acid, a dicarboxylic acid, a tricarboxylic acid, anα-hydroxycarboxylic acid, a β-hydroxycarboxylic acid, anα-ketocarboxylic acid, or a combination thereof. In an aspect, thecarboxylic acid may be a C₁ to C₁₅ monocarboxylic acid or a C₁ to C₅monocarboxylic acid; alternatively, a C₁ to C₁₅ dicarboxylic acid or aC₁ to C₅ dicarboxylic acid; alternatively, a C₁ to C₁₅ tricarboxylicacid or a C₁ to C₅ tricarboxylic acid; alternatively, a C₁ to C₁₅α-hydroxycarboxylic acid or a C₁ to C₅ α-hydroxycarboxylic acid;alternatively, a C₁ to C₁₅ β-hydroxycarboxylic acid or a C₁ to C₅β-hydroxycarboxylic acid; or alternatively, a C₁ to C₁₅ α-ketocarboxylicacid or a C₁ to C₅ α-ketocarboxylic acid; or alternatively anycombination thereof. In aspects, the carboxylic acid may be amulti-carboxylic acid. As utilized herein, multi-carboxylic includescarboxylic acids comprising two or more carboxylic acid groups.

In an aspect, the titanium-containing solution comprises a carboxylicacid selected from the group consisting of acetic acid, formic acid,citric acid, gluconic acid, glycolic acid, glyoxylic acid, lactic acid,malic acid, malonic acid, oxalic acid, propionic acid, phosphonoaceticacid, tartaric acid, and combinations thereof. In yet a further aspect,the titanium-containing solution comprises oxalic acid.

In an aspect of the titanium-containing solution, the amino acid isglycine, dimethylglycine, arginine, aspartic acid, or serine, and thecarboxylate is provided by a carboxylic acid. In an aspect of thetitanium-containing solution, the amino acid is glycine,dimethylglycine, arginine, aspartic acid, or serine, and the carboxylateis provided by a carboxylic acid selected from the group consisting ofacetic acid, formic acid, citric acid, gluconic acid, glycolic acid,glyoxylic acid, lactic acid, malic acid, malonic acid, oxalic acid,propionic acid, phosphonoacetic acid, tartaric acid, and combinationsthereof. In an aspect of the titanium-containing solution, the aminoacid is glycine, dimethylglycine, arginine, aspartic acid, or serine,and the carboxylate is provided by oxalic acid.

When used as described herein, the carboxylate can be present in thetitanium-containing solution (e.g., ATS) in an amount of about 0.5 toabout 10 mol of carboxylate per mol of Ti present, alternatively, in anamount of about 1 to about 5 mol of carboxylate per mol of Ti present;alternatively in an amount of about 1.5 to about 4 mol of carboxylateper mol of Ti present; or alternatively in an amount of about 1 to about2.5 mol of carboxylate per mol of Ti present.

The source of titanium to be incorporated into the titanium-containingsolution (e.g., an ATS) may be any titanium compound capable ofproviding a sufficient amount of titanium to the olefin polymerizationcatalyst and the pre-catalyst composition thereof. In a further aspect,the titanium-containing compound comprises a tetravalent titanium(Ti(IV)) compound or a trivalent titanium (Ti(III)) compound. The Ti(IV)compound may be any compound that comprises Ti(IV); alternatively, theTi(IV) compound may be any compound that is able to release a Ti(IV)species upon dissolving into the solvent to form the titanium-containingsolution (e.g., ATS). The Ti(III) compound may be any compound thatcomprises Ti(III); alternatively, the Ti(III) compound may be anycompound that is able to release a Ti(III) species upon dissolving intothe solvent to form the titanium-containing solution (e.g., ATS). In anaspect the titanium compound is a Ti(IV) compound that hydrolyzes uponcontact with an aqueous solution to yield hydrated titania (e.g., asfreshly precipitated titania in the aqueous solution that can be furtherdissolved by inclusion of an amino acid and optionally a carboxylate(e.g., carboxylic acid) in the aqueous solution as shown in the Examplesbelow). In an aspect the titanium compound is a Ti(IV) compound thathydrolyzes upon contact with an aqueous solution to yield hydratedtitania is a titanium alkoxide.

In an aspect, the titanium-containing compound suitable for use in thetitanium-containing solution (e.g., ATS) of the present disclosurecomprises a titanium alkoxide. In aspects, the titanium-containingcompound comprises a Ti(IV) compound comprising at least one alkoxidegroup; or alternatively, at least two alkoxide groups. Ti(IV) compoundssuitable for use in the present disclosure include, but are not limitedto, Ti(IV) compounds that have the general formula Ti(OR)₄, TiO(OR)₂,Ti(OR)₂(acac)₂, Ti(OR)₂(oxal), or a combination thereof, wherein each Ris independently ethyl, isopropyl, n-propyl, isobutyl, or n-butyl;“acac” is acetylacetonate; and “oxal” is oxalate. Alternatively, thetitanium-containing compound comprises a titanium(IV) alkoxide. In anaspect, the titanium(IV) alkoxide can be titanium(IV) ethoxide,titanium(IV) isopropoxide, titanium(IV) n-propoxide, titanium(IV)n-butoxide, titanium(IV) 2-ethylhexoxide, or a combination thereof. In aparticular aspect, the titanium-containing compound can be titanium(IV)isopropoxide.

In an aspect, the titanium-containing compound suitable for use in thetitanium-containing solution (e.g., ATS) of the present disclosurecomprises a Ti salt such as oxylate, lactate, citrate, glycolate,tartrate, etc.

In a still further aspect, the titanium-containing compound suitable foruse in the present disclosure can comprise hydrous titania, titaniumhydroxide, titanium dioxide, titanic acid, titanyl sulfate, titaniumacetylacetonate, titanium oxyacetylacetonate, or a combination thereof.

In yet another aspect, the titanium-containing compound suitable for usein the present disclosure can comprise a titanium(IV) halide,non-limiting examples of which include titanium tetrachloride, titaniumtetrabromide, titanium(IV) oxychloride, and titanium(IV) oxybromide. Ina further aspect the titanium(IV) halide can comprise a titaniumalkoxyhalide having the general formula Ti(OR)_(n)Q_(4-n); wherein eachR independently is ethyl, isopropyl, n-propyl, isobutyl, or n-butyl;wherein Q may be a fluoride, a chloride, a bromide, an iodide, or acombination thereof; and wherein n may be an integer from 1 to 4.

In aspects, the titanium compound can be formed in situ in the aqueoustitanium solution. For example, in aspects, forming an aqueous titaniumsolution comprising a titanium compound having the formulaTi(acac)₂(OR)₂ comprises in situ formation of the titanium compoundhaving the formula Ti(acac)₂(OR)₂ by the combination of acetylacetone(acac) and a titanium precursor having the formula Ti(OR)₄ duringformation of the aqueous titanium solution.

In an aspect, the titanium compound has the formula Ti(OR)₄, TiO(OR)₂,Ti(OR)₂(acac)₂, or Ti(OR)₂(oxal), wherein “acac” is acetylacetonate,“oxal” is oxalate, and each R independently is ethyl, isopropyl,n-propyl, isobutyl, or n-butyl. In an aspect, the titanium compound is atitanium (IV) compound selected from the group consisting of Ti(OH)₄,TiO(OH)₂, TiO₂, TiO(oxalate)₂, and combinations thereof, or a titanium(III) compound selected from the group consisting of Ti₂(SO₄)₃,Ti(OAc)₃, Ti(oxalate)₃, Ti(NO₃)₃, and combinations thereof.

An amount of titanium present in an olefin polymerization catalyst ofthe present disclosure may range from about 0.01 wt. % to about 10 wt.%; alternatively, from about 0.5 wt. % to about 5 wt. %; alternatively,from about 1 wt. % to about 4 wt. %; or alternatively, from about 2 wt.% to about 4 wt. % titanium based upon the total weight of the olefinpolymerization catalyst. In another aspect, the amount of titaniumpresent in the olefin polymerization catalyst may range from about 1 wt.% to about 5 wt. % titanium based upon the total weight of the olefinpolymerization catalyst. Herein, a titanium percentage refers to aweight percent (wt. %) of titanium associated with the olefinpolymerization catalyst based upon the total weight of the olefinpolymerization catalyst after completion of all processing steps (i.e.,after activation via calcination). In a further aspect, an amount oftitanium present in a pre-catalyst composition of the present disclosuremay range from about 0.01 wt. % to about 25 wt. %; alternatively, fromabout 0.1 wt. % to about 20 wt. %; alternatively, from about 0.5 wt. %to about 10 wt. %; alternatively, from about 1 wt. % to about 6 wt. %;or alternatively, from about 2 wt. % to about 4 wt. % titanium basedupon a total weight of silica within the pre-catalyst. Herein, atitanium percentage refers to a weight percent (wt. %) of titaniumassociated with the pre-catalyst composition based upon a total weightof silica within the pre-catalyst composition after completion of allprocessing steps excluding activation via calcination.

The components of the titanium-containing solution (e.g., ATS) can becombined in any suitable order known to those of skill in the art andwith the help of this disclosure. For example, in an aspect, an ATS isprepared by sequential addition of a titanium-containing compound asdisclosed herein to the amino acid or aqueous amino acid mixture, whichmay optionally also comprise a peroxide or a carboxylate. In analternative aspect, the titanium-containing compound and the amino acidmay be contacted and subsequently contacted with the solvent (e.g.,water) to form the titanium-containing solution (e.g., ATS) as disclosedherein. In a further aspect, the titanium compound can be dissolved inthe amino acid and solvent (e.g., water) and optionally peroxide addedthereto. In a further aspect, the titanium compound can be dissolved inthe carboxylate (e.g., carboxylic acid) and the amino acid and solvent(e.g., water) added thereto.

In a particular aspect, the aqueous titanium solution (ATS) suitable foruse in the present disclosure may be characterized by a pH of less thanabout 5.5. Alternatively, the ATS may be characterized by a pH in arange of from about 2.5 to about 5.5; alternatively, from about 3.0 toabout 5.0; or alternatively, from about 3.5 to about 4.5.

In an aspect of the present disclosure, a method for preparation of anolefin polymerization catalyst or pre-catalyst composition comprisescontacting a silica support or a chromium-silica support with thetitanium-containing solution (e.g., an ATS) to form a titanated supportor a titanated/chrominated support.

A catalyst (e.g., a Cr/Si—Ti olefin polymerization catalyst) and apre-catalyst composition thereof of the present disclosure comprise asupport material that comprises silica (i.e., silicon dioxide, SiO₂),which is referred to herein a silica support. The silica supportprovides a solid substrate that provides physical/structural support forthe catalytic metals (e.g., Cr and Ti) of the pre-catalyst compositionand the resultant catalyst (e.g., olefin polymerization catalyst). Thesilica support may be any silica support suitable for preparation of theolefin polymerization catalyst and the pre-catalyst composition thereofas disclosed herein. The silica support may be a naturally occurringmaterial comprising silica or a synthetic material comprising silica.The silica support may be prepared using any suitable method, e.g., thesilica support may be prepared by hydrolyzing tetrachlorosilane (SiCl₄)with water or by contacting sodium silicate and a mineral acid. In aparticular aspect, the silica support may be a produced by a gelmanufacturing process (e.g., a sol-gel process), which may provide ahydrogel silica support or a xerogel silica support. Silica supportsproduced via gel manufacturing processes can be dried prior to contactwith any other catalyst components (e.g., drying a hydrogel to form axerogel).

The silica support suitable for use in the present disclosure maycontain greater than about 50 wt. % silica; alternatively, greater thanabout 80 wt. % silica; or alternatively, greater than about 95 wt. %silica based upon the total weight of the silica support. In an aspect,the silica support comprises an amount of silica in a range of fromabout 70 wt. % to about 95 wt. % based upon a total weight of the silicasupport.

The silica support may include additional components that do notadversely affect the catalyst, such as zirconia, alumina, thoria,magnesia, fluoride, sulfate, phosphate, or a combination thereof. In aparticular aspect, the silica support of the present disclosurecomprises alumina, and may be referred to as a silica-alumina support(i.e., a SiO₂/Al₂O₃ support).

Non-limiting examples of silica supports suitable for use in thisdisclosure include ES70, which is a silica support material with asurface area of 300 m²/gram and a pore volume of 1.6 cm³/gram, that iscommercially available from PQ Corporation; V398400, which is a silicasupport material that is commercially available from Evonik; and theSYLOPOL® family of silica supports commercially available from W. R.Grace & Co.

The silica support suitable for use in the present disclosure may have asurface area and a pore volume effective to provide for the productionof an active olefin polymerization catalyst. In an aspect of the presentdisclosure, the silica support possesses a surface area in a range offrom about 100 m²/gram to about 1000 m²/gram; alternatively, from about250 m²/gram to about 1000 m²/gram; alternatively, from about 250 m²/gramto about 700 m²/gram; alternatively, from about 250 m²/gram to about 600m²/gram; or alternatively, greater than about 250 m²/gram. The silicasupport may be porous and further characterized by a pore volume ofgreater than about 0.9 cm³/gram; alternatively, greater than about 1.0cm³/gram; or alternatively, greater than about 1.5 cm³/gram. In anaspect of the present disclosure, the silica support is characterized bya pore volume in a range of from about 1.0 cm³/gram to about 2.5cm³/gram. The silica support may be further characterized by an averageparticle size in a range of from about 10 microns to about 500 microns;alternatively, about 25 microns to about 300 microns; or alternatively,about 40 microns to about 150 microns. Generally, an average pore sizeof the silica support may be in a range of from about 10 Angstroms (Å)to about 1000 Angstroms (Å). In one aspect of the present disclosure,the average pore size of the silica support is in a range of from about50 Angstroms (Å) to about 500 Angstroms (Å); alternatively, from about75 Angstroms (Å) to about 350 Angstroms (Å).

The silica support may be present in the olefin polymerization catalystand a pre-catalyst composition thereof in an amount in a range of fromabout 50 wt. % to about 99 wt. %; or alternatively, from about 80 wt. %to about 99 wt. %. Herein a silica support percentage refers to a weightpercent (wt. %) of the silica support associated with the olefinpolymerization catalyst based upon the total weight of the olefinpolymerization catalyst after completion of all processing steps (i.e.,after activation via calcination). Alternatively, the silica supportpercentage refers to a weight percent (wt. %) of the silica supportassociated with the pre-catalyst based upon the total weight of thepre-catalyst after completion of all relevant processing steps excludingactivation via calcination.

In an aspect, preparation the catalyst (e.g., a Cr/Si—Ti olefinpolymerization catalyst) and the pre-catalyst composition thereofexcludes thermal treatment (e.g., drying) of the silica support prior tocontact with any other catalyst component (e.g., prior to contact withthe titanium-containing solution (e.g., ATS) and/or prior to contactwith a chromium-containing compound). In an embodiment where the silicasupport is a xerogel silica support, the xerogel is not subjected toadditional drying after formation of the xerogel (e.g., after formation,a xerogel silica support may absorb some ambient moisture which is notremoved by further drying prior to contact with any other catalystcomponent). Consequently, the silica support suitable for use in thepresent disclosure may be a termed a hydrated silica support. Withoutwishing to be limited by theory, the hydrated silica support comprises asilica support wherein water evolution occurs when the silica support isheated within a range of from about 180° C. to about 200° C. undervacuum conditions for a period of time ranging from about 8 hours toabout 20 hours. In a further aspect, the silica support may contain fromabout 0.1 wt. % to about 20 wt. % water; alternatively, about 1 wt. % toabout 20 wt. % water; alternatively, about 1 wt. % to about 10 wt. %water; or alternatively, about 0.1 wt. % to about 10 wt. % water basedupon the total weight of the silica support.

In alternative aspects, the silica support may be a dried silicasupport, and the method of making the pre-catalyst composition canfurther comprise drying a hydrated silica support to provide the driedsilica support, and the dried silica support can be subsequentlycontacted with one or more additional catalyst components (e.g.,contacted with the titanium-containing solution (e.g., ATS) and/orcontacted with a chromium-containing compound). The silica support canbe dried, for example, by heating the silica support to a temperature ina range of from about 150° C. to about 250° C. and maintaining thetemperature of the silica support in the range of from about 150° C. toabout 250° C. for a time period of from about 1 hour to about 24 hoursto form the dried support.

In a particular aspect of the present disclosure, a silica supportsuitable for use in the present disclosure comprises chromium. Thesilica support comprising chromium may be termed a chrominated silicasupport or a chromium-silica support (Cr—Si support or Cr-silicasupport). In another aspect, the chrominated support comprises thecharacteristics disclosed herein for the silica support whileadditionally containing chromium. A non-limiting example of thechrominated silica support is HA30W, which is a chromium-silica supportmaterial that is commercially available from W. R. Grace and Company. Inother aspects, a method of forming a pre-catalyst composition orcatalyst of this disclosure can further comprise contacting the silicasupport with a chromium-containing compound to form a chrominated silicasupport, and the chrominated silica support can be contacted with atitanium-containing solution (e.g., ATS) of the type disclosed herein.

In a still further aspect, an olefin polymerization catalyst and/or apre-catalyst composition thereof of the present disclosure comprisechromium. In such aspects, chromium can be incorporated into thepre-catalyst composition or the catalyst via the contacting of a silicasupport, a titanated support, a dried titanated support, or combinationsthereof with a chromium-containing compound (also referred to as achromium compound) to form the pre-catalyst composition, which can becalcined to form the polymerization catalyst. In an aspect, one or morechromium-containing compounds are added to the titanium-containingsolution (e.g., ATS), and chromium and titanium are added concurrentlyto the silica support by contact with the titanium-containing solution(e.g., ATS) that further comprises chromium.

The source of chromium may be any chromium-containing compound capableof providing a sufficient amount of chromium to the olefinpolymerization catalyst and the pre-catalyst composition thereof. In anaspect, the chromium-containing compound may be a water-soluble chromiumcompound or a hydrocarbon-soluble chromium compound. Examples ofwater-soluble chromium compounds include chromium trioxide, chromiumacetate, chromium nitrate, or a combination thereof. Examples ofhydrocarbon-soluble chromium compounds include tertiary butyl chromate,biscyclopentadienyl chromium(II), chromium(III) acetylacetonate, or acombination thereof. In one aspect of the present disclosure, thechromium-containing compound may be a chromium(II) compound, achromium(III) compound, or a combination thereof. Suitable chromium(III)compounds include, but are not limited to, chromium(III) carboxylates,chromium(III) naphthenates, chromium(III) halides, chromium(III)sulfates, chromium(III) nitrates, chromium(III) dionates, or acombination thereof. Specific chromium(III) compounds include, but arenot limited to, chromium(III) sulfate, chromium(III) chloride,chromium(III) nitrate, chromium(III) bromide, chromium(III)acetylacetonate, and chromium(III) acetate. Suitable chromium(II)compounds include, but are not limited to, chromium(II) chloride,chromium(II) bromide, chromium(II) iodide, chromium(II) sulfate,chromium(II) acetate, or a combination thereof.

An amount of chromium present in the olefin polymerization catalyst maybe in a range of from about 0.01 wt. % to about 10 wt. %; alternatively,from about 0.5 wt. % to about 5 wt. %; alternatively, from about 1 wt. %to about 4 wt. %; or alternatively, from about 2 wt. % to about 4 wt. %chromium based upon the total weight of the olefin polymerizationcatalyst. In another aspect, the amount of chromium present in theolefin polymerization catalyst may be in a range of from about 1 wt. %to about 5 wt. % chromium based upon the total weight of the olefinpolymerization catalyst. Herein, a chromium percentage refers to aweight percent (wt. %) of chromium associated with the olefinpolymerization catalyst based upon the total weight of the olefinpolymerization catalyst after completion of all processing steps (i.e.,after activation via calcination). In a further aspect, an amount ofchromium present in a pre-catalyst composition may be in a range of fromabout 0.01 wt. % to about 10 wt. %; alternatively, from about 0.1 wt. %to about 5 wt. %; alternatively, from about 0.2 wt. % to about 2 wt. %;or alternatively, from about 0.5 wt. % to about 1.5 wt. % chromium basedupon a total weight of silica within the pre-catalyst composition.Herein, a chromium percentage refers to a weight percent (wt. %) ofchromium associated with the pre-catalyst composition based upon thetotal weight of silica within the pre-catalyst after completion of allprocessing steps excluding activation via calcination.

In an aspect of the present disclosure the pre-catalyst or catalystcomponents disclosed herein may be contacted in any order or fashiondeemed suitable to one of ordinary skill in the art with the aid of thepresent disclosure to produce, respectively, a pre-catalyst compositionor an olefin polymerization catalyst having the characteristicsdisclosed herein.

In a particular aspect, a method of forming a pre-catalyst compositioncomprises: forming a titanium-containing solution (e.g., ATS) asdescribed herein comprising a solvent (e.g., water), an amino acid,optionally a peroxide, optionally a carboxylate, and a titanium compoundas described herein; contacting a chrominated silica support with thetitanium-containing solution (e.g., ATS) to form a titanated/chrominatedsupport; drying the titanated/chrominated support to form thepre-catalyst composition. The pre-catalyst composition can be calcined,as detailed further hereinbelow, to provide a polymerization catalyst.

In another particular aspect, a method of forming a pre-catalystcomposition comprises: forming a titanium-containing solution (e.g.,ATS) as described herein comprising a solvent (e.g., water), an aminoacid, optionally a peroxide, optionally a carboxylate, and a titaniumcompound as described herein; contacting a silica support with thetitanium-containing solution (e.g., ATS) to form a titanated support;contacting the titanated support with a chromium-containing compound asdescribed herein to provide a titanated/chrominated support; and dryingthe titanated/chrominated support to form the pre-catalyst composition.The pre-catalyst composition can be calcined, as detailed furtherhereinbelow, to provide a polymerization catalyst.

In another particular aspect, a method of forming a pre-catalystcomposition comprises: forming a titanium-containing solution (e.g.,ATS) as described herein comprising a solvent (e.g., water), an aminoacid, optionally a peroxide, optionally a carboxylate, and a titaniumcompound as described herein; simultaneous or sequentially contacting asilica support with the titanium-containing solution (e.g., ATS) and achromium-containing compound as described herein to form atitanated/chrominated support; and drying the titanated/chrominatedsupport to form the pre-catalyst composition. The pre-catalystcomposition can be calcined, as detailed further hereinbelow, to providea polymerization catalyst.

In another particular aspect, a method of forming a pre-catalystcomposition comprises: forming a titanium-containing solution (e.g.,ATS) as described herein comprising a solvent (e.g., water), an aminoacid, optionally a peroxide, optionally a carboxylate, a titaniumcompound as described herein, and a chromium-containing compound asdescribed herein; contacting a silica support with thetitanium-containing solution (e.g., ATS) further comprising thechromium-containing compound as described herein to form atitanated/chrominated support; and drying the titanated/chrominatedsupport to form the pre-catalyst composition. The pre-catalystcomposition can be calcined, as detailed further hereinbelow, to providea polymerization catalyst.

In another particular aspect, a method of forming a pre-catalystcomposition, the method comprising: forming an aqueous titanium solutionas described herein comprising water, an amino acid, optionally aperoxide, optionally a carboxylate, and a titanium compound as describedherein; contacting a silica support with the aqueous titanium solutionto form a titanated support; drying the titanated support to form adried titanated support; and contacting the dried titanated support witha chromium-containing compound as described herein for form atitanated/chrominated support and optionally drying thetitanated/chrominated support to form the pre-catalyst composition. Insuch aspects, drying the titanated/chrominated support to form thepre-catalyst composition can be effected by any means known to those ofskill in the art and with the help of this disclosure, and can beeffected as described hereinbelow. The pre-catalyst composition can becalcined, as detailed further hereinbelow, to provide a polymerizationcatalyst.

In another particular aspect, a method of forming a pre-catalystcomposition, the method comprising: forming an aqueous titanium solutionas described herein comprising water, an amino acid, optionally aperoxide, optionally a carboxylate, and a titanium compound as describedherein, and a chromium-containing compound as described herein;contacting a silica support with the aqueous titanium solution to form atitanated/chrominated support; optionally drying thetitanated/chrominated support to form the pre-catalyst composition. Insuch aspects, drying the titanated/chrominated support to form thepre-catalyst composition can be effected by any means known to those ofskill in the art and with the help of this disclosure, and can beeffected as described hereinbelow. The pre-catalyst composition can becalcined, as detailed further hereinbelow, to provide a polymerizationcatalyst.

In a particular aspect, a method of forming a pre-catalyst compositioncomprises: forming a titanium-containing solution (e.g., ATS) asdescribed herein comprising a solvent (e.g., water), an amino acid, aperoxide, and a titanium compound as described herein; contacting achrominated silica support with the titanium-containing solution (e.g.,ATS) to form a titanated/chrominated support; drying thetitanated/chrominated support to form the pre-catalyst composition. Thepre-catalyst composition can be calcined, as detailed furtherhereinbelow, to provide a polymerization catalyst.

In another particular aspect, a method of forming a pre-catalystcomposition, the method comprising: forming an aqueous titanium solutionas described herein comprising water, an amino acid, a peroxide, and atitanium compound as described herein; contacting a silica support withthe aqueous titanium solution to form a titanated support; drying thetitanated support to form a dried titanated support; and contacting thedried titanated support with a chromium-containing compound as describedherein for form a titanated/chrominated support and optionally dryingthe titanated/chrominated support to form the pre-catalyst composition.In such aspects, drying the titanated/chrominated support to form thepre-catalyst composition can be effected by any means known to those ofskill in the art and with the help of this disclosure, and can beeffected as described hereinbelow. The pre-catalyst composition can becalcined, as detailed further hereinbelow, to provide a polymerizationcatalyst.

In another particular aspect, a method of forming a pre-catalystcomposition, the method comprising: forming an aqueous titanium solutionas described herein comprising water, an amino acid, a peroxide, atitanium compound as described herein, and a chromium-containingcompound as described herein; contacting a silica support with theaqueous titanium solution to form a titanated/chrominated support;optionally drying the titanated/chrominated support to form thepre-catalyst composition. In such aspects, drying thetitanated/chrominated support to form the pre-catalyst composition canbe effected by any means known to those of skill in the art and with thehelp of this disclosure, and can be effected as described hereinbelow.The pre-catalyst composition can be calcined, as detailed furtherhereinbelow, to provide a polymerization catalyst.

In a particular aspect, a method of forming a pre-catalyst compositioncomprises: forming a titanium-containing solution (e.g., ATS) asdescribed herein comprising a solvent (e.g., water), an amino acid, acarboxylate, and a titanium compound as described herein; contacting achrominated silica support with the titanium-containing solution (e.g.,ATS) to form a titanated/chrominated support; drying thetitanated/chrominated support to form the pre-catalyst composition. Thepre-catalyst composition can be calcined, as detailed furtherhereinbelow, to provide a polymerization catalyst.

In another particular aspect, a method of forming a pre-catalystcomposition, the method comprising: forming an aqueous titanium solutionas described herein comprising water, an amino acid, a carboxylate, anda titanium compound as described herein; contacting a silica supportwith the aqueous titanium solution to form a titanated support; dryingthe titanated support to form a dried titanated support; and contactingthe dried titanated support with a chromium-containing compound asdescribed herein for form a titanated/chrominated support and optionallydrying the titanated/chrominated support to form the pre-catalystcomposition. In such aspects, drying the titanated/chrominated supportto form the pre-catalyst composition can be effected by any means knownto those of skill in the art and with the help of this disclosure, andcan be effected as described hereinbelow. The pre-catalyst compositioncan be calcined, as detailed further hereinbelow, to provide apolymerization catalyst.

In another particular aspect, a method of forming a pre-catalystcomposition, the method comprising: forming an aqueous titanium solutionas described herein comprising water, an amino acid, a carboxylate, anda titanium compound as described herein, and a chromium-containingcompound as described herein; contacting a silica support with theaqueous titanium solution to form a titanated/chrominated support;optionally drying the titanated/chrominated support to form thepre-catalyst composition. In such aspects, drying thetitanated/chrominated support to form the pre-catalyst composition canbe effected by any means known to those of skill in the art and with thehelp of this disclosure, and can be effected as described hereinbelow.The pre-catalyst composition can be calcined, as detailed furtherhereinbelow, to provide a polymerization catalyst.

In a particular aspect, a method of forming a pre-catalyst compositioncomprises: forming a titanium-containing solution (e.g., ATS) asdescribed herein comprising a solvent (e.g., water), an amino acid, aperoxide, a carboxylate, and a titanium compound as described herein;contacting a chrominated silica support with the titanium-containingsolution (e.g., ATS) to form a titanated/chrominated support; drying thetitanated/chrominated support to form the pre-catalyst composition. Thepre-catalyst composition can be calcined, as detailed furtherhereinbelow, to provide a polymerization catalyst.

In another particular aspect, a method of forming a pre-catalystcomposition, the method comprising: forming an aqueous titanium solutionas described herein comprising water, an amino acid, a peroxide, acarboxylate, and a titanium compound as described herein; contacting asilica support with the aqueous titanium solution to form a titanatedsupport; drying the titanated support to form a dried titanated support;and contacting the dried titanated support with a chromium-containingcompound as described herein for form a titanated/chrominated supportand optionally drying the titanated/chrominated support to form thepre-catalyst composition. In such aspects, drying thetitanated/chrominated support to form the pre-catalyst composition canbe effected by any means known to those of skill in the art and with thehelp of this disclosure, and can be effected as described hereinbelow.The pre-catalyst composition can be calcined, as detailed furtherhereinbelow, to provide a polymerization catalyst.

In another particular aspect, a method of forming a pre-catalystcomposition, the method comprising: forming an aqueous titanium solutionas described herein comprising water, an amino acid, a peroxide, acarboxylate, and a titanium compound as described herein, and achromium-containing compound as described herein; contacting a silicasupport with the aqueous titanium solution to form atitanated/chrominated support; optionally drying thetitanated/chrominated support to form the pre-catalyst composition. Insuch aspects, drying the titanated/chrominated support to form thepre-catalyst composition can be effected by any means known to those ofskill in the art and with the help of this disclosure, and can beeffected as described hereinbelow. The pre-catalyst composition can becalcined, as detailed further hereinbelow, to provide a polymerizationcatalyst.

In an aspect, contacting of the silica support (e.g., the hydratedsilica support, the dried silica support) or the chrominated silicasupport) with the titanium-containing solution (e.g., ATS) can beeffected by any suitable methodology known to one of skill in the artand with the help of this disclosure, such as ion-exchange, incipientwetness, spray drying, pore fill, aqueous impregnation, or the like.

In an aspect, contacting of the silica support (e.g., the hydratedsilica support, the dried support), the titanated silica support, and/orthe dried titanated silica support with the chromium-containing compoundcan be effected by any suitable methodology known to one of skill in theart and with the help of this disclosure, such as ion-exchange,incipient wetness, spray drying, pore fill, aqueous impregnation,organic solvent impregnation, melt coating, or the like.

In an aspect, contacting of the silica support (e.g., the hydratedsilica support, the dried silica support) with the titanium-containingsolution (e.g., ATS) that further comprises a chromium-containingcompound can be effected by any suitable methodology known to one ofskill in the art and with the help of this disclosure, such asion-exchange, incipient wetness, spray drying, pore fill, aqueousimpregnation, or the like.

In some aspects of the present disclosure, contacting of the componentsutilized in preparation of the olefin polymerization catalyst may becarried out in the presence of a reaction media. In a further aspect,the reaction media may be formed during contacting of the componentsutilized in preparation of the olefin polymerization catalyst. Thereaction media can comprise a solvent (e.g., water) as disclosed hereinand one or more liquids associated with the components utilized inpreparation of the olefin polymerization catalyst (e.g., waterassociated with the silica support). In an aspect, the reaction mediaexcludes any solid component utilized in the preparation of the olefinpolymerization catalyst disclosed herein (e.g., silica support and anysolids associated therewith). In some aspects, a sum of an amount ofwater present in the reaction media may be in a range of from about 1wt. % to about 99 wt. %; alternatively, from about 1 wt. % to about 50wt. %; alternatively, from about 1 wt. % to about 20 wt. %; oralternatively, from about 1 wt. % to about 10 wt. % based upon the totalweight of the reaction media. In yet a further aspect, the reactionmedia may contain greater than about 20 wt. % water; alternatively,about 40 wt. % water; alternatively, about 60 wt. % water;alternatively, about 80 wt. % water; or alternatively, about 90 wt. %water based upon the total weight of the reaction media wherein thewater may originate from one or more components utilized in preparationof the olefin polymerization catalyst.

Drying the support (e.g., the titanated support, the chrominated support(e.g., Cr-silica support), and/or the titanated/chrominated support) canbe effected by any means known to one of skill in the art and with thehelp of this disclosure. For example, drying can comprise heating thesupport to a temperature in a range of from about 25° C. to about 300°C.; alternatively, from about 50° C. to about 150° C.; or alternatively,from about 75° C. to about 100° C. Drying can further comprisemaintaining the temperature in the range of from about 25° C. to about300° C.; alternatively, from about 50° C. to about 150° C.; oralternatively, from about 75° C. to about 100° C. for a time period offrom about 30 minutes to about 6 hours to form a dried support (e.g.,which can, in aspects be the pre-catalyst composition). In aspects, forexample, drying can be optionally used to remove solvent introduced bythe addition of the titanium-containing compound and/or thechromium-containing compound and/or the presence of a reaction media. Adried chrominated, titanated support may be referred to as apre-catalyst that is suitable for activation (e.g., via calcining) tobecome a catalyst (e.g., an olefin polymerization catalyst).

In an aspect of the present disclosure, a method for preparation of anolefin polymerization catalyst further comprises activating apre-catalyst composition prepared as disclosed herein via a calcinationstep. In some aspects, calcination of the pre-catalyst compositioncomprises heating the pre-catalyst composition in an oxidizingenvironment to produce the olefin polymerization catalyst. For example,the pre-catalyst composition may be calcined by heating the pre-catalystcomposition in the presence of air to a temperature in a range of fromabout 400° C. to about 1000° C.; alternatively, from about 500° C. toabout 900° C.; or alternatively, from about 500° C. to about 850° C.Calcination of the pre-catalyst composition may further comprisemaintaining the temperature of the pre-catalyst composition in thepresence of air in the range of from about 400° C. to about 1000° C.;alternatively, from about 500° C. to about 900° C.; or alternatively,from about 500° C. to about 850° C. for a time period in a range of fromabout 1 minute to about 24 hours; alternatively, from about 1 minute toabout 12 hours; alternatively, from about 20 minutes to about 12 hours;alternatively, from about 1 hour to about 10 hours; alternatively, fromabout 3 hours to about 10 hours; or alternatively, from about 3 hours toabout 5 hours to produce the olefin polymerization catalyst.

Also disclosed herein are a titanated silica support, a pre-catalystcomposition and a polymerization catalyst produced as described herein.In an aspect, disclosed herein is a pre-catalyst comprising a silicasupport and (a) titanium in an amount ranging from about 0.01% to about10% by total weight of the pre-catalyst, wherein the titanium is presentwithin a surface layer on the silica support; (b) an amino acid in anamount ranging from about 0.1 to about 10 mol per mole of Ti present inthe pre-catalyst; and (c) optionally, (i) a peroxide, when present, inan amount ranging from about 0.1 to about 10 mol per mole of Ti presentin the pre-catalyst; or (ii) a carboxylate, when present, is in anamount ranging from about 0.5 to about 10 mol per mole of Ti present inthe pre-catalyst. In an aspect, the amino acid comprises threonine,serine, dimethylglycine, or a combination thereof. In an aspect, theperoxide comprises hydrogen peroxide, dicumyl peroxide, benzoylperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, a peroxyacid, aper-carboxylic acid, a perester, or a combination thereof. In an aspect,the pre-catalyst further comprises (d) chromium in an amount rangingfrom about 0.01% to about 10% by total weight of the pre-catalyst. In anaspect, the silica support comprises a surface area of from about 100m²/gram to about 1000 m²/gram and a pore volume of from about 1.0cm³/gram to about 2.5 cm³/gram.

Further disclosed herein is a method of producing a polymer, and apolymer produced via the method. The method of producing a polymercomprises contacting a polymerization catalyst as described herein witha monomer under conditions suitable for formation of the polymer; andrecovering the polymer. In aspects, the monomer comprises ethylene andthe polymer comprises polyethylene.

The olefin polymerization catalysts of the present disclosure aresuitable for use in any olefin polymerization method, using varioustypes of polymerization reactors. In an aspect of the presentdisclosure, a polymer of the present disclosure is produced by anyolefin polymerization method, using various types of polymerizationreactors. As used herein, “polymerization reactor” includes any reactorcapable of polymerizing olefin monomers to produce homopolymers and/orcopolymers. Homopolymers and/or copolymers produced in the reactor maybe referred to as resin and/or polymers. The various types of reactorsinclude, but are not limited to those that may be referred to as batch,slurry, gas-phase, solution, high pressure, tubular, autoclave, or otherreactor and/or reactors. Gas phase reactors may comprise fluidized bedreactors or staged horizontal reactors. Slurry reactors may comprisevertical and/or horizontal loops. High pressure reactors may compriseautoclave and/or tubular reactors. Reactor types may include batchand/or continuous processes. Continuous processes may use intermittentand/or continuous product discharge or transfer. Processes may alsoinclude partial or full direct recycle of un-reacted monomer, un-reactedcomonomer, olefin polymerization catalyst and/or co-catalysts, diluents,and/or other materials of the polymerization process.

Polymerization reactor systems of the present disclosure may compriseone type of reactor in a system or multiple reactors of the same ordifferent type, operated in any suitable configuration. Production ofpolymers in multiple reactors may include several stages in at least twoseparate polymerization reactors interconnected by a transfer systemmaking it possible to transfer the polymers resulting from the firstpolymerization reactor into the second reactor. Alternatively,polymerization in multiple reactors may include the transfer, eithermanual or automatic, of polymer from one reactor to subsequent reactoror reactors for additional polymerization. Alternatively, multi-stage ormulti-step polymerization may take place in a single reactor, whereinthe conditions are changed such that a different polymerization reactiontakes place.

The desired polymerization conditions in one of the reactors may be thesame as or different from the operating conditions of any other reactorsinvolved in the overall process of producing the polymer of the presentdisclosure. Multiple reactor systems may include any combinationincluding, but not limited to, multiple loop reactors, multiple gasphase reactors, a combination of loop and gas phase reactors, multiplehigh pressure reactors, and a combination of high pressure with loopand/or gas reactors. The multiple reactors may be operated in series orin parallel. In an aspect of the present disclosure, any arrangementand/or any combination of reactors may be employed to produce thepolymer of the present disclosure.

According to one aspect of the present disclosure, the polymerizationreactor system may comprise at least one loop slurry reactor. Suchreactors are commonplace, and may comprise vertical or horizontal loops.Generally, continuous processes may comprise the continuous introductionof a monomer, an olefin polymerization catalyst, and/or a diluent into apolymerization reactor and the continuous removal from this reactor of asuspension comprising polymer particles and the diluent. Monomer,diluent, olefin polymerization catalyst, and optionally any comonomermay be continuously fed to a loop slurry reactor, where polymerizationoccurs. Reactor effluent may be flashed to remove the liquids thatcomprise the diluent from the solid polymer, monomer and/or comonomer.Various technologies may be used for this separation step, including butnot limited to, flashing that may include any combination of heataddition and pressure reduction; separation by cyclonic action in eithera cyclone or hydrocyclone; separation by centrifugation; or otherappropriate method of separation.

Typical slurry polymerization processes (also known as particle-formprocesses) are disclosed in U.S. Pat. Nos. 3,248,179, 4,501,885,5,565,175, 5,575,979, 6,239,235, 6,262,191 and 6,833,415, for example;each of which are herein incorporated by reference in their entirety.

Diluents suitable for use in slurry polymerization include, but are notlimited to, the monomer being polymerized and hydrocarbons that areliquids under reaction conditions. Examples of suitable diluentsinclude, but are not limited to, hydrocarbons such as propane,cyclohexane, isobutane, n-butane, n-pentane, isopentane, neopentane, andn-hexane. Some loop polymerization reactions can occur under bulkconditions where no diluent is used. An example is the polymerization ofpropylene monomer as disclosed in U.S. Pat. No. 5,455,314, which isincorporated by reference herein in its entirety.

According to yet another aspect of the present disclosure, thepolymerization reactor may comprise at least one gas phase reactor. Suchsystems may employ a continuous recycle stream containing one or moremonomers continuously cycled through a fluidized bed in the presence ofthe olefin polymerization catalyst under polymerization conditions. Arecycle stream may be withdrawn from the fluidized bed and recycled backinto the reactor. Simultaneously, polymer product may be withdrawn fromthe reactor and new or fresh monomer may be added to replace thepolymerized monomer. Such gas phase reactors may comprise a process formulti-step gas-phase polymerization of olefins, in which olefins arepolymerized in the gaseous phase in at least two independent gas-phasepolymerization zones while feeding an olefin polymerizationcatalyst-containing polymer formed in a first polymerization zone to asecond polymerization zone. One type of gas phase reactor suitable foruse is disclosed in U.S. Pat. Nos. 4,588,790, 5,352,749, and 5,436,304,each of which is incorporated by reference in its entirety herein.

According to still another aspect of the present disclosure, ahigh-pressure polymerization reactor may comprise a tubular reactor oran autoclave reactor. Tubular reactors may have several zones wherefresh monomer, initiators, or olefin polymerization catalysts are added.Monomer may be entrained in an inert gaseous stream and introduced atone zone of the reactor. Initiators, olefin polymerization catalysts,and/or catalyst components may be entrained in a gaseous stream andintroduced at another zone of the reactor. The gas streams may beintermixed for polymerization. Heat and pressure may be employedappropriately to obtain optimal polymerization reaction conditions.

According to yet another aspect of the present disclosure, thepolymerization reactor may comprise a solution polymerization reactorwherein the monomer is contacted with the olefin polymerization catalystcomposition by suitable stirring or other means. A carrier comprising anorganic diluent or excess monomer may be employed. If desired, themonomer may be brought in the vapor phase and into contact with thecatalytic reaction product, in the presence or absence of liquidmaterial. The polymerization zone is maintained at temperatures andpressures that will result in the formation of a solution of the polymerin a reaction medium. Agitation may be employed to obtain bettertemperature control and to maintain uniform polymerization mixturesthroughout the polymerization zone. Adequate means are utilized fordissipating the exothermic heat of polymerization.

Polymerization reactors suitable for use in the present disclosure mayfurther comprise any combination of at least one raw material feedsystem, at least one feed system for an olefin polymerization catalystor catalyst components, and/or at least one polymer recovery system.Suitable reactor systems for the present disclosure may further comprisesystems for feedstock purification, catalyst storage and preparation,extrusion, reactor cooling, polymer recovery, fractionation, recycle,storage, loadout, laboratory analysis, and process control.

Conditions that are controlled for polymerization efficiency and toprovide polymer properties include, but are not limited to, temperature,pressure, type and quantity of the olefin polymerization catalyst orco-catalyst, and the concentrations of various reactants. Polymerizationtemperature can affect catalyst productivity, polymer molecular weightand molecular weight distribution. Suitable polymerization temperaturesmay be any temperature below the de-polymerization temperature,according to the Gibbs Free Energy Equation. Typically, this includesfrom about 60° C. to about 280° C., for example, and/or from about 70°C. to about 110° C., depending upon the type of polymerization reactorand/or polymerization process.

Suitable pressures will also vary according to the reactor andpolymerization process. The pressure for liquid phase polymerization ina loop reactor is typically less than 1000 psig (6.9 MPa). Pressure forgas phase polymerization is usually in a range of from about 200 psig(1.4 MPa)-500 psig (3.45 MPa). High-pressure polymerization in tubularor autoclave reactors is generally run in a range of from about 20,000psig (138 MPa) to 75,000 psig (518 MPa). Polymerization reactors canalso be operated in a supercritical region occurring at generally highertemperatures and pressures. Operation at conditions above the criticalpoint as indicated by a pressure/temperature diagram (supercriticalphase) may offer advantages.

The concentration of various reactants can be controlled to producepolymers with certain physical and mechanical properties. The proposedend-use product that will be formed by the polymer and the method offorming that product may be varied to determine the desired finalproduct properties. Mechanical properties include, but are not limitedto tensile strength, flexural modulus, impact resistance, creep, stressrelaxation and hardness test values. Physical properties include, butare not limited to density, molecular weight, molecular weightdistribution, melting temperature, glass transition temperature,temperature melt of crystallization, density, stereoregularity, crackgrowth, short chain branching, long chain branching and rheologicalmeasurements.

The concentrations of monomer, comonomer, hydrogen, co-catalyst,modifiers, and electron donors are generally important in producingspecific polymer properties. Comonomer may be used to control productdensity. Hydrogen may be used to control product molecular weight.Co-catalysts may be used to alkylate, scavenge poisons and/or controlmolecular weight. The concentration of poisons may be minimized, aspoisons may impact the reactions and/or otherwise affect polymer productproperties. Modifiers may be used to control product properties andelectron donors may affect stereoregularity.

Polymers such as polyethylene homopolymers and copolymers of ethylenewith other mono-olefins may be produced in the manner described aboveusing the olefin polymerization catalysts prepared as described herein.Polymers produced as disclosed herein may be formed into articles ofmanufacture or end use articles using techniques known in the art suchas extrusion, blow molding, injection molding, fiber spinning,thermoforming, and casting. For example, a polymer resin may be extrudedinto a sheet, which is then thermoformed into an end use article such asa container, a cup, a tray, a pallet, a toy, or a component of anotherproduct. Examples of other end use articles into which the polymerresins may be formed include pipes, films, and bottles.

A method of the present disclosure comprises contacting an olefinpolymerization catalyst of the type described with an olefin monomerunder conditions suitable for the formation of a polyolefin andrecovering the polyolefin. In an aspect the olefin monomer is anethylene monomer and the polyolefin is an ethylene polymer(polyethylene).

Polyethylene prepared as described herein may be characterized by a highload melt index (HLMI), in a range of from about 1 g/10 min. to about1000 g/10 min.; alternatively, from about 3 g/10 min. to about 300 g/10min.; alternatively, from about 6 g/10 min. to about 100 g/10 min.; oralternatively, from about 15 g/10 min. to about 40 g/10 min.

The melt index (MI) represents the rate of flow of a molten polymerthrough an orifice of 0.0825 inch diameter when subjected to a force of2,160 grams at 190° C. as determined in accordance with ASTM D1238-82condition E. The I10 represents the rate of flow of a molten polymerthrough an orifice of 0.0825 inch diameter when subjected to a force of10,000 grams at 190° C. as determined in accordance with ASTM D1238-82condition N. The HLMI (high load melt index) represents the rate of flowof a molten polymer through an orifice of 0.0825 inch diameter whensubjected to a force of 21,600 grams at 190° C. as determined inaccordance with ASTM D1238-82 condition F.

Utilization of a titanium-containing solution (e.g., ATS) in thepreparation of an olefin polymerization catalyst of the presentdisclosure may be advantageous because the ATS can facilitate theassociation of titanium with a silica support in the presence of anaqueous solvent (e.g., water). Further advantages may occur when thetitanium-containing solution utilized to form the olefin polymerizationcatalyst comprises an aqueous solvent (e.g., water). The solubility oftitanium in the aqueous solvent may be sufficient to allow the use ofspray drying methodologies for contacting the ATS and a silica support.Spray drying as used herein refers to a method of producing a dry powderfrom a liquid or slurry by rapidly drying with a hot gas. Spray dryingmethodologies may be utilized in the preparation of olefinpolymerization catalysts in a continuous production method with thepotential to produce large volumes of olefin polymerization catalysts.Spray drying methodologies may also be utilized in the preparation ofolefin polymerization catalysts having a consistent particle sizedistribution.

Utilization of the titanium-containing solution comprising the aqueoussolvent (i.e., ATS) may permit use of a hydrated silica support andobviate the thermal treatment required for anhydrous methods of catalystpreparation, (e.g., drying a hydrated silica support prior to contactwith any other catalyst component).

The herein disclosed utilization of amino acid and optionally a peroxideor a carboxylate, as described herein, that are soluble in water butresist hydrolysis, enables binding of the titanium to a support duringthe production of a chromium-silica-titanium (Cr/Si—Ti) catalyst.Aqueous solutions of amino acid and optionally a peroxide or acarboxylate, as described herein, which are inexpensive, can be utilizedin the aqueous titanation of polymerization catalysts.

Highly reactive volatile organic compounds (HRVOC) may be emitted duringcatalyst production. HRVOCs play a role in the formation of ozone inozone nonattainment areas, i.e., areas that do not meet theEnvironmental Protection Agency's air quality standards for ground-levelozone. Consequently, processes that create HRVOC emissions may besubject to compliance with various state and federal regulationsregarding HRVOC emission, such as the HRVOC emissions cap and tradeprogram. Utilization of an aqueous titanium solution (ATS) to produce apre-catalyst composition and a polymerization catalyst as describedherein can results in the production of a reduced amount of HRVOCsduring catalyst production, e.g., due to the use of the aqueoussolution, rather than an organic solvent. The herein disclosed methodprovides an inexpensive, effective and efficient way of producing anolefin polymerization catalyst.

EXAMPLES

The following examples are given as particular aspects of the presentdisclosure and to demonstrate the practice and advantages thereof. It isunderstood that the examples are given by way of illustration and arenot intended to limit the specification or the claims to follow in anymanner.

In each experiment of the following examples HA30W, a Cr/silica catalystmade by W. R Grace, was titanated as described below then activated bycalcination in dry air at 650° C. for three hours. The final catalystscontained 3.5 wt % titanium.

Activity tests were conducted in a 2.2 liter steel reactor equipped witha marine stirrer running at 500 rpm. The reactor was surrounded by asteel jacket circulating water, the temperature of which was controlledby use of steam and water heat exchangers. These were connected in anelectronic feed-back loop so that the reactor temperature could bemaintained at +/−0.5° C. during the reaction.

Unless otherwise stated, a small amount (0.01 to 0.10 grams normally) ofthe solid chromium catalyst was first charged under nitrogen to the dryreactor. Next about 0.25 g of sulfate-treated alumina (600° C.) wasadded as a scavenger for poisons. Then 1.2 liter of isobutane liquid wascharged and the reactor heated up to the specified temperature, usually105° C. Finally, ethylene was added to the reactor to equal a fixedpressure, normally 550 psig (3.8 MPa), which was maintained during theexperiment. The stirring was allowed to continue for the specified time,usually around one hour, and the activity was noted by recording theflow of ethylene into the reactor to maintain the set pressure.

After the allotted time, the ethylene flow was stopped and the reactorslowly depressurized and opened to recover a granular polymer powder. Inall cases the reactor was clean with no indication of any wall scale,coating or other forms of fouling. The polymer powder was then removedand weighed. Activity was specified as grams of polymer produced pergram of solid catalyst charged per hour.

Control Example 1

For control experiments C1, C2, and C3: each mole of titaniumisopropoxide was dissolved in the indicated number of moles (“Mol/Ti” inTable 1) of oxalic acid in aqueous solution. This solution was thenimpregnated into HA30W catalyst, which was then dried and calcined at650° C. in air for three hours. The amount of titanium was 3.5 wt %loading on the catalyst. A first control C1 comprised no oxalic acid; asecond control C2 comprises 2 moles of oxalic acid per mole of titaniumisopropoxide; and a third control C3 comprised 3 moles of oxalic acidper mole of titanium isopropoxide.

For inventive experiments I1, I2, I3, and I4, the same amount oftitanium (3.5 wt % loading) was dissolved using the indicated number ofmoles of amino acid (“Mol/Ti” in Table 1). This solution was thenimpregnated into the HA30W catalyst which was then dried and calcined at650° C. in air for three hours. In inventive experiments I1 and I2, theaqueous solution comprised 4.5 moles of the amino acidN,N-dimethylglycine per mole of titanium isopropoxide; in inventiveexperiment I3 the aqueous solution comprised 2 moles of the amino acidthreonine per mole of titanium isopropoxide; and in inventive experimentI4 the aqueous solution comprised 3 moles of the amino acid threonineper mole of titanium isopropoxide. In inventive experiments I2 and I3,the aqueous solution further comprised 5 moles of hydrogen peroxide permole of titanium. In inventive examples I5 to I8, the aqueous solutioncomprised 2 moles of oxalic acid per mole of titanium in combinationwith 2 moles of glycine per mole of titanium (I5), 2 moles ofN,N-dimethylglycine per mole of titanium (I6), and 1.85 moles ofarginine per mole of titanium (I7 and I8).

Table 1 shows the components utilized in the control and inventiveexperiments, and also provides the yield (grams polyethylene per gramcatalyst), the activity (grams polyethylene per gram catalyst per hour),the high load melt index (HLMI in decigrams per minute, as measured byASTM D1238, condition 190/21.6, at 190° C. with a 21.6 kg weight), theI10 (decigrams per minute, as measured by the same technique with a 10kg weight), the melt index (MI in decigrams per minute, as measured byASTM D1238, condition 190/2.16, at 190° C. with a 2.16 kg weight), andthe shear (ratio of the HLMI to the MI).

TABLE 1 Induction Dissolved Time Yield Activity HLMI I10 MI Shear Runin: Mol/Ti (min) (g/g) (g/g-h) (dg/min) (dg/min) (dg/min) (HLMI/MI)Control Runs: C1 Oxalic Acid 0 11 2973 2973 5.45 0.87 0.0000 — C2 OxalicAcid 2 14 2877 2813 6.86 1.11 0.0000 — C3 Oxalic Acid 3 13 2933 30886.43 1.03 0.0000 — Inventive Runs: I1 Dimethyl 4.5 — 2749 2170 7.02 1.270.018 397 glycine I2 Dimethyl 4.5 16 3060 3165 5.91 1.03 0.013 469glycine I3 Threonine + 2 10 3019 3483 9.48 1.71 0.03 379 H₂O₂ I4Threonine + 3 10 3119 5347 12.7 2.27 0.04 301 H₂O₂ I5 Oxalic Acid + 2(oxalic) 15 3150 3098 13.6 2.67 0.092 148 Glycine 2 (glycine) I6 OxalicAcid + 2 (oxalic) 10 3297 3243 21.5 4.18 0.176 122 Dimethyl 2 (dimethylglycine glycine) I7 Oxalic Acid + 2 (oxalic) 17 3244 3089 14.4 2.640.078 185 Arginine 1.85 (arginine) I8 Oxalic Acid + 2 (oxalic) 13 31422945 12.8 2.35 0.058 222 Arginine 1.85 (arginine)

The experimental results show that an aqueous titanium solution (ATS)comprising an amino acid, as described herein, can be utilized tosuccessfully titanate a polymerization catalyst.

The experimental results show that an aqueous titanium solution (ATS) asdescribed herein can be utilized to successfully titanate apolymerization catalyst. Without intending to be limited by theory, itis believed that the presence of an amino acid of the type describedherein helps to prevent undesired “clumping” or agglomeration of thetitanium on the silica support during the drying and/or calcinationsteps. The clumped or agglomerated forms of titanium on the silicasupport do not provide a desired catalytic function in contrast to adispersed form of titanium on the silica support that does provide adesired catalytic function and resultant polymer characteristics (e.g.,increased melt index). Without intending to be limited by theory, it isbelieved that the amino acid may function to prevent degradation (e.g.,hydrolysis) of one or more intermediate titanium compounds (e.g.,titanium oxalate) formed during the catalyst preparation methodology(e.g., formation of the ATS, impregnation of the silica support with theATS, drying the impregnated support, and/or calcining the driedimpregnated support to yield a Cr/Si—Ti catalyst).

Additional Disclosure

The following enumerated aspects of the present disclosure are providedas non-limiting examples.

A first aspect which is a method of a method comprising contacting asilica support with a titanium-containing solution to form a titanatedsilica support, wherein the titanium-containing solution comprises atitanium compound, a solvent, and an amino acid.

A second aspect which is the method of the first aspect, furthercomprising drying the titanated support by heating the titanated supportto a temperature in a range of from about 50° C. to about 200° C. andmaintaining the temperature of the titanated support in the range offrom about 50° C. to about 200° C. for a time period of from about 30minutes to about 6 hours to form a pre-catalyst.

A third aspect which is the method of the second aspect, furthercomprising contacting a chromium-containing compound with the silicasupport, the titanated silica support, the pre-catalyst, or combinationsthereof.

A fourth aspect which is the method of the first aspect, wherein thesilica support comprises chromium.

A fifth aspect which is the method of the first aspect, wherein thesilica support is simultaneously contacted with the titanium-containingsolution and a chromium-containing compound.

A sixth aspect which is the method of the fifth aspect, wherein thetitanium-containing solution comprises the chromium-containing compound.

A seventh aspect which is the method of any of the third to the sixthaspects, wherein the chromium-containing compound comprises chromiumtrioxide, chromium acetate, chromium nitrate, chromium sulfate, tertiarybutyl chromate, biscyclopentadienyl chromium(II), chromium(III)acetylacetonate, or combinations thereof.

An eighth aspect which is the method of any of the first to the seventhaspects, wherein the solvent is selected from the group consisting ofwater, alcohol, and combinations thereof.

A ninth aspect which is the method of any of the first to the eighthaspects, wherein the solvent is an aqueous solvent.

A tenth aspect which is the method of any of the first to the ninthaspects, wherein the titanium compound comprises a titanium (IV)compound, a titanium (III) compound, titania, or combinations thereof.

An eleventh aspect which is the method of any of the first to the tenthaspects, wherein the titanium compound comprises a titanium(IV) compoundcomprising an alkoxide group.

A twelfth aspect which is the method of the eleventh aspect, wherein thetitanium compound has the formula Ti(OR)₄, TiO(OR)₂, Ti(OR)₂(acac)₂, orTi(OR)₂(oxal), wherein “acac” is acetylacetonate, “oxal” is oxalate, andeach R independently is ethyl, isopropyl, n-propyl, isobutyl, orn-butyl.

A thirteenth aspect which is the method of the tenth aspect, wherein thetitanium (IV) compound comprises Ti(OH)₄, TiO(OH)₂, TiO₂, TiO(oxalate)₂,or a combination thereof, and wherein the titanium (III) compoundcomprises Ti₂(SO₄)₃, Ti(OAc)₃, Ti(oxalate)₃, Ti(NO₃)₃, or a combinationthereof.

A fourteenth aspect which is the method of any of the first to thethirteenth aspects, wherein the amino acid comprises an alpha (α) aminoacid, a beta (β) amino acid, or a combination thereof, wherein an αamino acid is an amino acid having an amino group and a carboxyl groupattached to the alpha carbon, and wherein a β amino acid is an aminoacid in which the amino group is attached to the secondary carbon.

A fifteenth aspect which is the method of any of the first to thefourteenth aspects, wherein the amino acid comprises threonine, serine,dimethylglycine, or a combination thereof.

A sixteenth aspect which is the method of any of the first to thefifteenth aspects, wherein the titanium-containing solution furthercomprises a peroxide.

A seventeenth aspect which is the method of the sixteenth aspect,wherein the peroxide comprises hydrogen peroxide, dicumyl peroxide,benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, aperoxyacid, a per-carboxylic acid, a perester, or a combination thereof.

An eighteenth aspect which is the method of any of the first to theseventeenth aspects, wherein the titanium-containing solution furthercomprises a carboxylate.

A nineteenth aspect which is the method of the eighteenth aspect,wherein the carboxylate comprises a multi carboxylate, an alpha-hydroxycarboxylate, or a combination thereof.

A twentieth aspect which is the method of the eighteenth aspect, whereinthe carboxylate is provided by a carboxylic acid selected from the groupconsisting of acetic acid, formic acid, citric acid, gluconic acid,glycolic acid, glyoxylic acid, lactic acid, malic acid, malonic acid,oxalic acid, propionic acid, phosphonoacetic acid, tartaric acid, andcombinations thereof.

A twenty-first aspect which is the method of any of the first to thetwentieth aspects, wherein the silica support has a surface area of fromabout 100 m²/gram to about 1000 m²/gram and a pore volume of from about1.0 cm³/gram to about 2.5 cm³/gram.

A twenty-second aspect which is the method of the third aspect, furthercomprising calcining the pre-catalyst by heating the pre-catalyst in areducing atmosphere to a temperature in a range of from about 400° C. toabout 1000° C. and maintaining the temperature of the pre-catalyst inthe range of from about 400° C. to about 1000° C. for a time period offrom about 1 minute to about 24 hours to form a catalyst.

A twenty-third aspect which is a method comprising contacting achrominated silica support with a aqueous titanium solution to form atitanated/chrominated silica support, wherein the aqueous titaniumsolution comprises water, a titanium compound, and an amino acid, dryingthe titanated/chrominated silica support by heating thetitanated/chrominated silica support to a temperature in a range of fromabout 50° C. to about 200° C. and maintaining the temperature of thetitanated/chrominated silica support in the range of from about 50° C.to about 200° C. for a time period of from about 1 second to about 6hours, alternatively from about 30 minutes to about 6 hours, to form apre-catalyst, and calcining the pre-catalyst by heating the pre-catalystin an oxidizing atmosphere (e.g., in the presence of oxygen such as air)to a temperature in a range of from about 400° C. to about 1000° C. andmaintaining the temperature of the pre-catalyst in the range of fromabout 400° C. to about 1000° C. for a time period of from about 1 minuteto about 24 hours to form a catalyst.

A twenty-fourth aspect which is the method of the twenty-third aspect,wherein the aqueous titanium is prepared by (i) preparing a firstsolution by combining the amino acid and water; (ii) adding the titaniumcompound (e.g., a titanium alkoxide such as titanium isopropoxide) tothe first solution to form a second solution; and (iii) optionallyadding a peroxide (e.g., hydrogen peroxide) to the first or secondsolutions.

A twenty-fifth aspect which is the method of the twenty-fourth aspect,further comprising contacting a chromium-containing compound with asilica support to form the chrominated silica support, wherein thechromium-containing compound comprises chromium trioxide, chromiumacetate, chromium nitrate, chromium sulfate, tertiary butyl chromate,biscyclopentadienyl chromium(II), chromium(III) acetylacetonate, orcombinations thereof.

A twenty-sixth aspect which is a titanated silica support prepared bythe method of the first aspect.

A twenty-seventh aspect which is a pre-catalyst prepared by the methodof the third aspect.

A twenty-eighth aspect which is a catalyst produced by the method of thetwenty-second aspect.

A twenty-ninth aspect which is the pre-catalyst of the twenty-seventhaspect, wherein an amount of titanium present in the pre-catalyst rangesfrom about 0.01% to about 10% by total weight of the pre-catalyst and anamount of chromium present in the pre-catalyst ranges from about 0.01%to about 10% by total weight of the pre-catalyst.

A thirtieth aspect which is the catalyst of the twenty-eighth aspect,wherein an amount of titanium present in the catalyst ranges from about0.01% to about 10% by total weight of the catalyst and an amount ofchromium present in the catalyst ranges from about 0.01% to about 10% bytotal weight of the catalyst.

A thirty-first aspect which is a pre-catalyst comprising a silicasupport and (a) titanium in an amount ranging from about 0.01% to about10% by total weight of the pre-catalyst, wherein the titanium is presentwithin a surface layer on the silica support, (b) an amino acid in anamount ranging from about 0.1 to about 10 mol per mole of Ti present inthe pre-catalyst; and (c) optionally, (i) a peroxide, when present, inan amount ranging from about 0.1 to about 10 mol per mole of Ti presentin the pre-catalyst, or (ii) a carboxylate, when present, is in anamount ranging from about 0.5 to about 10 mol per mole of Ti present inthe pre-catalyst.

A thirty-second aspect which is the pre-catalyst of the thirty-firstaspect, wherein the amino acid comprises threonine, serine,dimethylglycine, or a combination thereof.

A thirty-third aspect which is the pre-catalyst of the thirty-first orthe thirty-second aspect, wherein the peroxide comprises hydrogenperoxide, dicumyl peroxide, benzoyl peroxide, t-butyl hydroperoxide,di-t-butyl peroxide, a peroxyacid, a per-carboxylic acid, a perester, ora combination thereof.

A thirty-fourth aspect which is the pre-catalyst of any of thethirty-first to the thirty-third aspects, further comprising (d)chromium in an amount ranging from about 0.01% to about 10% by totalweight of the pre-catalyst.

A thirty-fifth aspect which is the pre-catalyst of any of thethirty-first to the thirty-fourth aspects, wherein the silica supportcomprises a surface area of from about 100 m²/gram to about 1000 m²/gramand a pore volume of from about 1.0 cm³/gram to about 2.5 cm³/gram.

A thirty-sixth aspect which is a method of producing polyethylene,comprising contacting the catalyst of the twenty-fifth aspect withethylene under conditions suitable for formation of polyethylene; andrecovering the polyethylene.

The terms “a”, “an”, and “the” are intended, unless specificallyindicated otherwise, to include plural alternatives, e.g., at least one.Herein, while methods and processes are described in terms of“comprising” various components or steps, the methods and processes canalso “consist essentially of” or “consist of” the various components orsteps. A particular feature of the disclosed subject matter can bedisclosed as follows: Feature X can be A, B, or C. It is alsocontemplated that for each feature the statement can also be phrased asa listing of alternatives such that the statement “Feature X is A,alternatively B, or alternatively C” is also an aspect of the presentdisclosure whether or not the statement is explicitly recited.

While various aspects of the present disclosure have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the presentdisclosure. The aspects of the present disclosure described herein areexemplary only and are not intended to be limiting. Many variations andmodifications of the present disclosure are possible and are within thescope of the present disclosure. Where numerical ranges or limitationsare expressly stated, such express ranges or limitations should beunderstood to include iterative ranges or limitations of like magnitudefalling within the expressly stated ranges or limitations (e.g., “fromabout 1 to about 10” includes, 2, 3, 4, etc.; “greater than 0.10”includes 0.11, 0.12, 0.13, etc.). Use of the term “optionally” withrespect to any element of a claim is intended to mean that the subjectelement is required, or alternatively, is not required. Bothalternatives are intended to be within the scope of the claim. Use ofbroader terms such as “comprises”, “includes”, “having”, etc. should beunderstood to provide support for narrower terms such as “consistingof”, “consisting essentially of”, “comprised substantially of”, etc.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an aspect of thepresent disclosure. Thus, the claims are a further description and arean addition to the aspect of the present disclosure. The discussion of areference in the present disclosure is not an admission that it is priorart to the present disclosure, especially any reference that may have apublication date after the priority date of this application. Thepresent disclosures of all patents, patent applications, andpublications cited herein are hereby incorporated by reference, to theextent that they provide exemplary, procedural or other detailssupplementary to those set forth herein.

All publications, patent applications, and patents mentioned herein areincorporated by reference in their entirety. In the event of conflict,the present specification, including definitions, is intended tocontrol. With respect to all ranges disclosed herein, such ranges areintended to include any combination of the mentioned upper and lowerlimits even if the particular combination is not specifically listed.

What is claimed is:
 1. A method of preparing a polymerization catalystcomprising: (i) contacting a chrominated silica support with an aqueoustitanium solution to form a titanated/chrominated silica support,wherein the aqueous titanium solution comprises water, a titaniumcompound, and an amino acid; (ii) drying the titanated/chrominatedsilica support by heating the titanated/chrominated silica support to atemperature in a range of from about 50° C. to about 200° C. to form apre-catalyst; and (iii) calcining the pre-catalyst by heating thepre-catalyst to a temperature in a range of from about 400° C. to about1000° C. to form the polymerization catalyst.
 2. The method of claim 1wherein the aqueous titanium solution is prepared by (i) preparing afirst solution by combining the amino acid and water; (ii) adding thetitanium compound to the first solution to form a second solution. 3.The method of claim 2 further comprising adding a peroxide to the firstsolution or second solution.
 4. The method of claim 1 wherein thetitanium compound comprises a titanium (IV) compound, a titanium (III)compound, titania, or combinations thereof.
 5. The method of claim 4wherein the titanium (IV) compound comprises an alkoxide group.
 6. Themethod of claim 1 wherein the titanium compound has a formula Ti(OR)4,TiO(OR)2, Ti(OR)2(acac)2, or Ti(OR)2(oxal), wherein “acac” isacetylacetonate, “oxal” is oxalate, and each R independently is ethyl,isopropyl, n-propyl, isobutyl, or n-butyl.
 7. The method of claim 4wherein the titanium (IV) compound comprises Ti(OH)4, TiO(OH)2, TiO2,TiO(oxalate)2, or a combination thereof, and wherein the titanium (III)compound comprises Ti2(SO4)3, Ti(OAc)3, Ti(oxalate)3, Ti(NO3)3, or acombination thereof.
 8. The method of claim 1 wherein an amount oftitanium present in the polymerization catalyst ranges from about 0.01%to about 10% by total weight of the polymerization catalyst.
 9. Themethod of claim 1 wherein an amount of chromium present in thepolymerization catalyst ranges from about 0.01% to about 10% by totalweight of the polymerization catalyst.
 10. The method of claim 1 whereinthe amino acid comprises an alpha (α) amino acid, a beta (β) amino acid,or a combination thereof, wherein an α amino acid is an amino acidhaving an amino group and a carboxyl group attached to an alpha carbon,and wherein a β amino acid is an amino acid in which the amino group isattached to a secondary carbon.
 11. The method of claim 1 wherein theamino acid comprises threonine, serine, dimethylglycine, or acombination thereof.
 12. The method of claim 3 wherein the peroxidecomprises hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, t-butylhydroperoxide, di-t-butyl peroxide, a peroxyacid, a per-carboxylic acid,a perester, or a combination thereof.
 13. The method of claim 2 furthercomprising adding a carboxylate to the first solution, the secondsolution or both wherein the carboxylate comprises a multi carboxylate,an alpha-hydroxy carboxylate, or a combination thereof.
 14. The methodof claim 13 wherein the carboxylate is provided by a carboxylic acidselected from the group consisting of acetic acid, formic acid, citricacid, gluconic acid, glycolic acid, glyoxylic acid, lactic acid, malicacid, malonic acid, oxalic acid, propionic acid, phosphonoacetic acid,tartaric acid, and combinations thereof.
 15. The method of claim 3further comprising adding a carboxylate to the first solution, thesecond solution or both wherein the carboxylate comprises a multicarboxylate, an alpha-hydroxy carboxylate, or a combination thereof. 16.The method of claim 3 wherein the carboxylate is provided by acarboxylic acid selected from the group consisting of acetic acid,formic acid, citric acid, gluconic acid, glycolic acid, glyoxylic acid,lactic acid, malic acid, malonic acid, oxalic acid, propionic acid,phosphonoacetic acid, tartaric acid, and combinations thereof.
 17. Amethod of preparing a polymerization catalyst comprising: (i) preparinga first solution comprising water, a titanium-containing compound and acarboxylic acid; (ii) preparing a second solution comprising the firstsolution and an amino acid; (iii) contacting a chrominated silicasupport with the second solution to form a titanated/chrominated silicasupport; (iv) drying the titanated/chrominated silica support to form apre-catalyst; and (v) calcining the pre-catalyst to form thepolymerization catalyst.
 18. The method of claim 17 wherein the aminoacid comprises threonine, serine, dimethylglycine, or a combinationthereof.
 19. The method of claim 17 wherein the carboxylic acidcomprises acetic acid, formic acid, citric acid, gluconic acid, glycolicacid, glyoxylic acid, lactic acid, malic acid, malonic acid, oxalicacid, propionic acid, phosphonoacetic acid, tartaric acid, orcombinations thereof.
 20. The method of claim 17 further comprisingadding a peroxide to the first solution or second solution, wherein theperoxide comprises hydrogen peroxide, dicumyl peroxide, benzoylperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, a peroxyacid, aper-carboxylic acid, a perester, or a combination thereof.